Cardiovascular-related disorders are a leading cause of death in developed countries. In the US alone, one cardiovascular death occurs every 34 seconds and cardiovascular disease-related costs are approximately $250 billion. Current methods for treatment of vascular disease include chemotherapeutic regimens, angioplasty, insertion of stents, reconstructive surgery, bypass grafts, resection of affected tissues, or amputation. Unfortunately, for many patients, such interventions show only limited success, and many patients experience a worsening of the conditions or symptoms.
These diseases often require reconstruction and replacement of blood vessels. Currently, the most popular source of replacement vessels is autologous arteries and veins. However, such autologous vessels are in short supply or are not suitable especially in patients who have had vessel disease or previous surgeries.
Synthetic grafts made of materials such, as PTFE and Dacron are popular vascular substitutes. Despite their popularity, synthetic materials are not suitable for small diameter grafts or in areas of low blood flow. Material-related problems such as stenosis, thromboembolization, calcium deposition, and infection have also been demonstrated.
Therefore, there is a clinical need for biocompatible and biodegradable structural matrices that facilitate tissue infiltration to repair/regenerate diseased or damaged tissue. In general, the clinical approaches to repair damaged or diseased blood vessel tissue do not substantially restore their original function. Thus, there remains a strong need for alternative approaches for tissue repair/regeneration that avoid the common problems associated with current clinical approaches.
The emergence of tissue engineering may offer alternative approaches to repair and regenerate damaged/diseased tissue. Tissue engineering strategies have explored the use of biomaterials in combination with cells, growth factors, bioactives and bioreactor processes to develop biological substitutes that ultimately can restore or improve tissue function. The use of colonizable and remodelable scaffolding materials has been studied extensively as tissue templates, conduits, barriers, and reservoirs. In particular, synthetic and natural materials in the form of foams, and textiles have been used in vitro and in vivo to reconstruct/regenerate biological tissue, as well as deliver agents for inducing tissue growth.
Such tissue-engineered blood vessels (TEBVs) have been successfully fabricated in vitro and have been used in animal models. However, there has been very limited clinical success.
Regardless of the composition of the scaffold and the targeted tissue, the template must possess some fundamental characteristics. The scaffold must be biocompatible, possess sufficient mechanical properties to resist the physical forces applied at the time of surgery, porous enough to allow cell invasion, or growth, easily sterilized, able to be remodeled by invading tissue, and degradable as the new tissue is being formed. Furthermore, the scaffold may be fixed to the surrounding tissue via mechanical means, fixation devices, or adhesives. So far, conventional materials, alone or in combination, lack one or more of the above criteria. Accordingly, there is a need for scaffolds that can resolve the potential pitfalls of conventional materials.